It isn't soley up to the operator or manufacturer to ground an aircraft, certainly not until some cause has been identified, either through investigation or info passed by the crew before the crash.
As pilots, we must all resist any pressure to fly if we had doubts about the aircraft. If you aren't completely happy to fly it (and it seems that many of you have concerns) then I feel you could hardly been criticised for refusing to fly the S-92. Personally, I don't fly the S-92 and have little knowledge of the previous MGB problems that others are referring to, so as an aircraft I feel it has a safe enough track record to keep it flying. But if you have genuine doubts, I wouldn't get into an aircraft I wasn't happy with and neither should any of us.
If I remember correctly, Sikorski opted to go without the complicated Emergency Gear Box lubrication that newer aircraft were developing, and went for a Bypass System not unlike the L1 Super Puma ? Is that the case or am I behind the times ?